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Tuesday, December 29, 2015

Q. A quick question about a newly planted Agave stricta. Within 2 weeks of
planting the spines have begun turning brown from the tips down. Do these
plants generally brown out in the cold or is this one dying? It is a 15 gal plant
- purchased from a local cactus nursery. It had some brown on a few stems shen
purchased, but not like this. It was planted according to the instructions from
the nursery with a sand/soil mix at bottom and sand around the perimeter.

It is found growing in southeastern Mexico in its native
habitat at about 5000 feet from what I could find. San Marcos nursery says it
will handle temperatures down to at least 20° F. This is for Agave stricta
‘Nana’ so I am wondering if this is what you have or not.

A. stricta is confused with A.
striata a lot because they look almost identical. This particular cactus may
benefit if it's not placed in a location where it receives very hot direct sunlight
in the afternoon. It sounds like it is a little bit delicate perhaps because of
where it grows and its elevation.

I am thinking you may have one
of two or three things going on with yours. I don't think it's temperature. If
this cactus was growing in a shaded or semi shaded area and then placed into an
area that receives a lot of direct sunlight in the late afternoon it's possible
that it could be sun damage.

How you planted this cactus
sounds fine but if you are watering it too often, even with good drainage, this
could also cause problems. When water is scarce it relies on internal storage
of water. During the summer I would not water it more than every three weeks if
you are planning to push some growth.

If you're happy with that size,
you can water it less often than that. It is also possible that the soil mix
that was used could have been a little too saline. Flush the soil with several
gallons of water a few times to remove any excess salts if you think this might
be a problem.

But I do not think it is a
temperature damage but more likely to be sun damage or damage from irrigation.
During the winter you should be able to water only once or twice during the
entire winter.

Further thinking, it is POSSIBLE it could be a salinity problem. There are soil mixes out there that use sands with lots of salts in them and they are not washed sands. Wash plenty of water through the soil where you planted a couple of times a few weeks apart to reduce salt problems. Now is a good time to do that because temperatures are cold and tolerance to lots of water in the soil is much higher in plants during cool or colder weather.

It is possible it might have dieback during some extremely cold winters but it should re-sprout easily from its base once it has established for one season. Like any Acacia I worry a little bit about allergies from its pollen. It is a rather large plant usually grown as a shrub but I think you could train it into a small tree fairly easily. It should handle our soils with little problems just make sure that you amend the soil at the time of planting with compost.

Saturday, December 26, 2015

I have seen garden editors right that there is very
little to do in January. How wrong! This is a very busy time of the year for
vegetable production. In our cold desert climate with warm days and cold nights
some of the best vegetables of the year are produced. Cool and cold winter
temperatures slow growth of plants which concentrates flavors and reduces
bitterness in many of our cool season vegetables.

Germination from
seed. As long as temperatures are warm enough during the day, seed
germination of cool season vegetables may take longer but they will germinate
if the soil is warm enough. Loose, dark, fluffy soils are warmer than heavy soils.
Work in enough compost so that the soils are no longer compacted. Warm air
during the day must be able to enter the soil through loose pores to warm it.

Select vegetable
seed of known varieties that have performed well in the past or have been
recommended to you by others who are good gardeners. Don’t use varieties of
seed that are unknown to you unless you just want an experience and don’t care
about the end result.

Know the
temperature of your soil. This is important because diseases that are
dormant in the soil may affect some vegetable varieties if the soil temperature
is borderline for them. Beans are a good example and may fail due to root diseases
if planted in soils that are too cold.

Prepare the area to be planted with seed with a high
phosphorus fertilizer of your choice. Triple super phosphate is a good choice
for conventional gardeners. Bone meal, bat guano, mushroom compost are good choices
for organic gardeners.

Cover soils to be
planted with clear or black plastic to warm the soil. I prefer clear
plastic. Cover the soil with plastic two or three days before planting. Pin the
edges of the plastic to the soil. Cover the edges of the plastic with soil so
the wind does not lift the plastic. Just before planting cut slits in the
plastic where seed is to be placed and leave the plastic on the soil surface
until plants have germinated or longer.

Pre-germination of
vegetable seed initiates seed germination. Pre-germinating the seed is
wetting the seed long enough for a long enough period so the seed absorbs
water. This is the first step in germination. The seed is kept in water at room
temperature for 6 to 12 hours. The seed is then removed from the water and the
surface dried in the air or with paper towels. The seed should be planted as
soon as it is dry enough to plant.

Planting depth of seed is related to its size. Very tiny
seeds are placed on the surface and covered lightly with soil. Larger seed are
planted in the soil to a depth twice its diameter.

On Saturday, January 9, 2016, I will be at the Twenty-Nine Palms Inn in Twenty-Nine Palms, California, to present a fruit tree pruning workshop. I will also be discussing how to apply fertilizers and what kind and pest control operations that should be performed this time of year. The workshop will begin promptly at 9 AM. I will bring along some fertilizers for fruit trees and EDDHA iron chelates from Viragrow in Las Vegas for those interested. Contact me if you need me to bring along anything else that might not be available locally.

Q. I have three mature
California fan palms, aged at least twenty years, planted quite close to each
other and located in Mesquite, Nevada. Two or three years ago, one showed signs
of early leaf browning and soon died. Now leaves of others are quite yellow but
stems and new growth at the top of the tree is green. I'm afraid they are going
the same way as the one that died! Disease?

Yellowing palm leaves of the reader

A. I do not think the
yellowing and scorching is directly related to disease. I think it is primarily
a soil or plant nutrient problem that will not be solved simply by adding
fertilizers. Irrigation might be part of the problem IF the trees are watered
too often. In your particular case, I think several things may be going on at
once.

I’m
a big proponent of soil improvement when planting anything in our desert soils.
In Mojave Desert soils, and soils brought in as fill around homes in housing
developments, soil improvement at the time of planting is an absolute must even
if you are planting cactus.

Desert soils are usually very low in organic matter like this soil. The light tan color of the soil is an indicator of a very low percent of organics in the soil.

If
your soil is tan colored or very light brown, there is zero organic matter in
that soil. Palms are typically planted without much consideration for any kind
of soil improvement. They are planted in tiny holes, the roots surrounded with
very little if any improved soil. Once planted, the soil surrounding the plant
is covered with rock mulch.

In
this type of soil environment roots suffocate and die over time. If they don’t
die in the first couple of years, they have a great deal of difficulty taking
up the proper nutrients from the soil even if fertilizers are applied. They
become unhealthy.

The
plants react to this poor soil environment by turning yellow. It’s not a
disease caused by disease organisms directly but the plant color indicates they
are in poor health.

To
correct this problem, add organic material to the soil surrounding the roots
and improve water drainage and movement of air into the soil. Until this is
done, you will see very little improvement to these plants just by adding
fertilizer.

In
the past we used a technique called “vertical mulching”. It is no longer talked
about much anymore but it was effective. Vertical mulching created vertical
holes to a depth of 2 to 3 feet around the plant in the root area. These
vertical holes were filled with improved soil.

Vertical
holes were created using a high-pressure watering device or a post hole digger.
Pull back the rock mulch where you are going to create vertical holes a foot or
two from the trunk. Create the holes using a post hole digger or water from a
high-pressure nozzle to a depth of 2 to 3 feet. Be careful of irrigation lines.

Fill
these holes with a 50-50 mixture of the soil you took out of the hole mixed with
compost, minus any rocks larger than a golf ball. Create a minimum of four
holes around these trees. Use these spots in the future to add fertilizer once
a year. Apply more compost on the surface to further improve soil at the
surface and put back the rock mulch.

Make
sure plastic is not on the soil surface surrounding the plants and under any
mulch. Plastic on the soil surface can create similar problems.

Fruit tree pruning. I gave several classes on fruit tree pruning in December. I will be giving is in Twentynine Palms, California, on Saturday, January 9 beginning at 9 AM at the Twentynine Palms Inn. You can read about it on their blog soon or on my blog.

The major topics I covered included size control and improving fruit production. I divide fruit tree pruning into two operations for those just learning how to prune fruit trees; first of all control the size of the tree and establish its general architecture or structure and secondly prune to improve fruit production.

Fertilizing fruit trees. Fertilize fruit trees in our climate any time in January before the first week in February or before the signs of new growth if you are not in our climate. If you are late by a couple of weeks you can still do it. Use conventional fertilizers or compost.

Use any fertilizer that is designated as a fruit tree fertilizer. In a pinch, you can substitute a rose fertilizer. Follow the label directions.

If you were in my class, I would show you how to "read" a tree to determine how much fertilizer to apply. If you don't know, follow established guidelines that you trust. You can apply it on top of mulch or pull the mulch back and put it on top of the soil, then replacing the mulch.

Make sure that you water it in enough to get the fertilizer in contact with wet soil. That last statement, in wet soil, is very important. Fertilizer cannot move to the roots if it is not in contact with water.

Example of a dormant oil
available from Viragrow

Be careful how much phosphorus, the middle number, you apply. Phosphorus can hang around in soils a long time and it can build up concentrations if you aren't careful. Apply it only once during a growing season.

Controlling pests. Applying a dormant oil at least once, if not twice, during the winter is a very important preventive pest control application. It is aimed at aphids, scale insects, spider mites and a few other general pests that might appear this coming growing season.

It is primarily aimed at "suffocating" these insects so it is important to apply it on a warm day with no wind. It is best applied by high pressure pesticide application equipment. However if you are using a backpack sprayer or other pressurized sprayer keep the pressure as high as you can during the application. This will help the oil cover as much surface as possible without leaving any gaps.

Solo backpack sprayer

Low-pressure equipment or hose and sprayers "spit" out the oil which makes for a very uneven application and wastes a lot of the dormant oil. Dormant oils for homeowners are nearly always lightweight summer oils that are much less dangerous to plants than some of the winter oils applied in decades past.

Don't spray unless you have a problem or you had a problem last year and you're trying to get a jump ahead.

Mature leaf footed plant bug

A prominent pest on fruit and vegetables last year was the leaf footed plant bug.Your landscape right now. Look for the adults that will be ready to lay eggs on your plants as soon as it is warm and they have some surface area.

They will most likely hangout right now on broadleaf evergreen trees such as bottlebrush. They can see you coming and will move away from you as you approach the tree or plant.

The adults have wings so they will be flying in from neighbors when temperatures start to warm up. Sprays that contain pyrethrin or the synthetic pyrethrins are a good choice on these critters.

As a last resort, Sevin insecticide will control them but use that conventional insecticide when you have exhausted other possibilities such as oils, soap sprays and pyrethrin products.

I have a lot more information but you have to start asking questions if you want it.

Q. Our family owns an
unimproved lot at about 8500 feet in southern Utah. A combination of heavy
snowfall, strong winds and disease resulted in blow down of dead and live
trees. We are planning to clear the area to reduce the potential of fire and then
seed native plants and wildflowers seeds. I cannot find any appropriate seed
available to do this.

A. There are seed packets
available locally and online labeled as wildflowers. But these are generic
wildflowers and not all native to our area. You are right to be looking for
seed appropriate to your area. Generic types of wildflower seeds should not be
used for seeding near semi-primitive or primitive areas.

Introducing
plants that are not native will result in future problems. Some non-native
plants can invade undeveloped areas and “choke out” native plants. This results in
multiple, successive future problems for other plants and animals relying on
native plants.

I
am not concerned so much whether this variety of apple tree will grow here or
not. It will. My main concern is the quality of the fruit it produces in our
climate and soils. Just because you like Macintosh apple you purchased from a
local grocery store does not mean that a Macintosh apple grown here will taste
the same. There are numerous potential problems with a Newtown apple grown in the desert. Only time will tell.

Yellow
Newtown Pippin has not had a long enough performance history in our climate to
recommend it for the general public. It ripens a little bit before Granny Smith
and a month or so before Pink Lady and this is a good time for apples to ripen
in our climate. However, other influences such as our soils and climate while
it was growing will impact its quality.

The following is a Release from the U.S. Forest Service and Nevada Division of Forestry regarding a new pest found in firewood in southern Nevada. This pest will leave the firewood and may attack pine trees in southern Nevada, in particular Mondale and Aleppo pines. From the sound of it, infested firewood was brought in from California into southern Nevada. If you think you have purchased some of this wood please contact the Nevada Division of Forestry for more information about what to do.Goto Nevada Division of Forestry Contact Information in Las Vegas

I
was alerted by Jeff Knight from NDA that the Mediterranean pine engraver, Orthotomicus
erosus (Wollaston), has been positively identified from two locations in
southern Nevada. One site was near Blue Diamond and the other was a firewood
distributor in Las Vegas. The identification was confirmed by Jim LaBonte
of the Oregon Dept. of Agriculture. The beetles were trapped in Lindgren
funnels with ethanol and alpha pinene as lures. This represents the first
record of this beetle in the U.S. outside of California. The beetle
appears to very aggressively attack stressed trees and rarely attack healthy
trees. The suspected host near Blue diamond is Pinus monophylla,
no suspect in for the Las Vegas site yet. Attached is the USFS Pest Alert
for the beetle. Further investigation of these sites will take place in
early Jan. to determine possible hosts and entrance into Nevada. At this time
NDA will not pursue any regulatory/quarantine actions, but will be working on
educational information on the insect.

Q. We use a white,
breathable fabric for some of our tender desert plants when there's a chance of
freezing temperatures. We're at a 3000
foot elevation on the eastern slope of the Spring Mountain Range and
temperatures can be 8° F more or less than those reported at McCarren International Airport. We go by the plant description temperatures and for 30 degree forecasts we cover those that could be damaged down to 20 F degrees. Can the fabric be left on continuously for long periods of time even
though nighttime temps are higher than 32 degrees if it's anticipated that in a week
or two or more temperatures will drop again below freezing? Some folks who sell this product say
it can be left on all winter but I thought I had better check with you.

Row crop cover used for cold protection for vegetable row crops

A. Yes you can leave it on! This
is a major advantage with these types of products specifically made for protecting
plants from light freezes. They are called by several different names including
crop covers, floating row covers, frost blankets and floating row crop covers.

Some
background on these products will help you understand them. These covers are flexible,
nearly transparent, extremely lightweight and made from fabrics that are typically
spun or woven.

They
“breathe” allowing light, rain and air movement through them but still capture
heat coming from the ground. They transmit so much light that there shading
effect on plants is only somewhere around 15 to 20%.

They
gained fame primarily in commercial vegetable production about 30 years ago for
two distinct reasons; protection of vegetables from light frosts and earlier
production. When left on permanently during cool weather, they can raise air
temperatures under the fabric about 5 to 6° F which causes vegetables to grow
faster which in turn means they can be harvested earlier.

Besides
protecting young tender plants from freezing temperatures and growing faster,
they also provide another valuable advantage; insect protection. In organic
production they are a valuable asset to leafy greens that can be damaged from
wind, intense sunlight or chewing insects.

Row crop covers are placed over new seedlings or
transplants and kept from blowing away with metal staples and a soil covering
the edges. They are also used as a covering for low tunnels used in vegetable
production.

Q. I am on our landscape committee for A Henderson HOA.
We are going to remove many dead and diseases trees in our small community.
Mostly privets that through the years have died after we converted to desert
landscape from grass. Others are mainly ash trees that are diseased and or have
dead limbs and with pruning look terrible. Most of our yards face either East
or West. We have been advised to replace the trees with fruitless olives or living
oak. All yards are small and have rock mulch. As many other communities we are
cash poor and need to make a wise decision because it will be expensive. We are
looking for evergreen, shade trees if possible.

I forwarded this question to Andrea Meckley, a Certified
Horticulturist working in the Las Vegas area since 1992.

A. I understand
your situation with the privet trees doing poorly. Since you are going through the expense of
replacement I realize you want to make good choices. Below are a few thoughts:

1. Fruitless Olives:

Pros: evergreen, little leave drop

Cons:
slow grower, sometimes they will fruit even though they are not supposed
to. If this happens you can apply a
solution to stop them from fruiting if it concerns you

Tuesday, December 15, 2015

Q.
Is it best to remove all the leaves from the soil after they have fallen or
leave them on the soil as mulch for fruit trees? My concern is about insects
that might stay there during the winter and cause damage in the spring.

fr

From reader

A.
In a very general sense I have two concerns regarding leaving undecomposed
leaves at the base of plants. You are right, the first one is insect problems
and it's very possible some insects will overwinter under loose leaves that
have not decomposed.

Remember to pick up any fruit lying
on the ground as well. Do not leave dried fruit on fruit trees because of
potential insect problems.

One insect in particular is the
grape leaf skeletonizer. Don’t leave debris around the base of grape plants
because of this insect problem. Make sure leaves are shredded or composted. If
you have one, lawnmowers are efficient leaf shredders.

The second potential problem is disease.
There are a few diseases that cut overwinter on fallen leaves. It is always
better to compost or shred leaves if you're going to leave them around the base
of plants. Sanitation in the garden is important.

Q.
It seems no matter what brand of potting soil, I have to bake it before I can
use it. If I don't, I get hundreds of tiny flies that hatch and swarm. I put
out water to catch and drown them. I spray insect oil on top of the soil
several times a day. I'm so afraid I'll kill the plants.

A.
Yes, fungus gnats in particular are a big problem in potting soils used for
houseplants. The younger generations feed off of both decaying plants and soft,
succulent living roots. They aren’t very particular about what they feed on,
living or dead, so long as it is soft, juicy and tender.

If fungus gnats are extremely happy in
their environment they will multiply very rapidly and cause poor growth and
stunting. Besides, they are pesky and a nuisance inside the house. If potting
soil is sterilized by the manufacturer using a heat treatment it should kill
all of the fungus gnats and should pose no problem.

Control fungus gnats with organic pest
control products such as beneficial nematodes that go after their destructive larvae
and a bacterium is also available with a similar result. You should be able to
find these products in your local nursery or garden center.

Yellow or blue sticky traps also work. I received this video on how to make yellow sticky traps from a friend.

Another effective method is to sterilize
this potting soil yourself by placing it, moistened, into a clear plastic bag
and let it bake in the sun. Temperatures need to get up to about 160 F for at
least 30 minutes for good control.

Another option is to apply pyrethrin sprays
to the soil and water it in.

Q.
We fertilize all of our bushes early spring and mid fall with a 5-10-5 liquid
plant tonic. Hopefully this isn't too much
nitrogen.

This concentrated fertilizer
has no nitrogen but very
high percentages of phosphorus
and potassium

A.
There are two ways to look at this question. Applying too much nitrogen can
mean either applying it too often or applying too much in a single application.
If you follow label directions, the amount of nitrogen applied should be
correct. Apply nitrogen as often as 8 weeks apart if you want continuous growth.

Applying excessive amounts of nitrogen can damage plants or cause excessive growth of leaves and stems.

When judging how much fertilizer to
apply and how often, observe the plant. If the plant does not have good growth
or the flower size and numbers have diminished, apply fertilizers or “plant
tonics” if you prefer.

Applying too much nitrogen, the first
number, is not normally a long-term problem. The potential long-term problem involves the over application of the second or
middle number, phosphorus.

Phosphorus stays bound in many soils for much longer
periods of time than nitrogen. Apply fertilizers containing high levels of
phosphorus (middle number) less often than fertilizers that contain high levels
of nitrogen.

As a general rule of thumb, apply
fertilizers containing phosphorus once a yearto established plants, two weeks
before flowering. The rest of the time use high nitrogen fertilizers.

The exception is at planting time. Every
time seed or transplants go in the ground, apply a high phosphorus fertilizer.
Before planting, mix high phosphorus fertilizers in the soil to the same depth
the roots will grow.

Bagged compost can be hard to find. Most
bagged products that contain compost are
soil mixes, not straight compost.

Consider using compost instead of a
mineral fertilizer. I am talking about compost which is harder to find, not a
soil mix that contains compost. Most composts have a good balance of nitrogen,
phosphorus and potassium and can be used as a substitute for mineral
fertilizers.

Composts provide plants with a lot of
minor elements not found in mineral fertilizers. Compost lowers soil
alkalinity, stimulates good soil microorganisms and provides humus or “black
gold” to the soil. It is a very powerful addition to desert soils.

Q.
We repotted a house plant that was constantly wilting and that seems to help.
Is it possible that the plant is too large and needs a “haircut”?

A.
Potted plants benefit from root pruning as well as top pruning if it is
possible to do so. I guess we could call this a “haircut”. Both the top of the
plant and its roots should be “in balance” with each other. We sometimes refer
to this as a plant’s “root to shoot ratio”.

Not all plants can be root pruned and top
pruned to make them smaller so they perform better in their container. Some
plants will need a larger container. Some plants are made smaller by “dividing”
the plants. Plants that require division are removed from their container and
separating a “clump” of plants into individual plants with a sharp, sanitized
knife or pruning saw. The cut ends are dipped into a fungicide before
replanting.

Some plants require renewal through
propagation. Typically these plants are propagated using methods such as stem cuttings, leaf cuttings, root cuttings or layering. These specialized
propagation techniques are specific to certain plants. The Internet is a good
source of information on propagating interior or houseplants.

Did you know that the roots of plants can be pruned? This is called root pruning and dramatically alters the root to shoot ratio of plants.

Root pruning, what is it?
As the name suggests, root pruning is the cutting of roots. It is done for different reasons than pruning the tops of plants. We have total access to the tops of plants. Axis to the roots of plants is much more limited. Roots grow differently from stems. Roots do not have buds. You can virtually cut anywhere on a root and it will "sucker" unlike many of the stems of trees and shrubs.

Why root prune?
The most common reasons for root pruning include controlling the size of the plant, slowing the growth of plants, initiate flowering, keep the roots closer to the trunk, keep the roots out of problem areas or creating problems.

This is a root pruning machine used in nursery practices for undercutting trees growing in the field under production.This machine is driven so that the young trees are undamaged as they pass under and between the tracks. The U-shaped blade is pulled behind this machine and undercuts the roots...root pruning... to make a bare root fruit tree that will transplant to the field with fewer losses. Photo taken by me at Dave Wilson Nursery www.davewilson.com

Root pruning is commonly done in the nursery operations where trees and shrubs are grown to be transported for planting in a new location. Root pruning is common in bonsai to reduce the growth of plants and keep them small. Root pruning is done in some greenhouse operations for similar reasons to nursery operations.

If root pruning is not done and the top of the plant dies or is severely pruned back, then the top regrows again very quickly to its original size. Once it reaches this size, growth slows again. This is the plants way of reestablishing what we have called the root to shoot ratio of the plant. The plant "recognizes" the difference in size between the top growth and undisturbed root size. The plant directs its growth, the flow of carbohydrates and hormones, to the top of the plant at the expense of growth in the roots.How can I use Root to shoot ratios?
If a plant is growing too rapidly and you want to slow it down, root prune it. Take a sharp shovel and sever the roots by pushing it through the soil and through the roots as deep as possible.

Do you want to keep the roots of plants from entering the septic tank or other problem areas? Root prune between the plant and the problem area. Root prune every 2 to 3 years.

Some diseases are transmitted from plant to plant when the roots fused together and what are called "root grafts". This commonly occurred in American elm with the transmission of Dutch elm disease. Root pruning can isolate plants from trees that are carrying the disease. If an Apple or Pear tree dies from fire blight, root prune the area around the dead tree to prevent the transmission of the disease through root grafts.

When Retrofitting trees and shrubs from a lawn area to drip irrigation, consider root pruning these trees and shrubs to generate roots closer to the trunk were the emitters are placed.

Having trouble with the tree flowering? Try root pruning to create a new root to shoot ratio that might slow the top growth and induce flowering.

Q. I am not sure how long some of my trees can go without
water during the winter. I have a mature Pepper, Mesquite and some palms that I
have not watered for 10 days because of the cold temperatures. Is 10 days
between watering okay?

A. 10 days between waterings should be no problem for
trees and large shrubs provided they were given a deep watering prior to this.
Deep rooted plants, like most trees and large shrubs, can go without water for
a longer period of time than smaller plants. Deep watering means flooding the soil with water to a depth of 2 to 3 feet. If drip is used then making sure enough volume of water is applied to soak to a depth of 2 to 3 feet.

Applying water with drip emitters this close to the trunk is okay for the first couple of years. As this tree gets larger, more emitters will be placed underneath the canopy of this tree and further from the trunk. About half the area under the canopy should receive water. Apply enough water in a single application to wet the soil to a depth of 2 to 3 feet.

Many landscapes have small
plants and big plants on the same circuit or valve. This means the small plants
cannot be watered separately from the larger plants. The small plants require
water more often. This forces the larger plants to be watered frequently even
when they don’t require it.

This twisted Acacia would be considered a desert tree. Putting a tree like this on an irrigation circuitFor desert plants gives greater flexibility when applying water. Applying water more often causes it to grow faster, larger and more dense. Applying water less often keeps it smaller, growing more slowly with fewer leaves.

Secondly, plants that do not
originally grow in desert climates must be watered more often than plants which
do. The mesquite and California pepper are both desert-type trees where water
can be withheld for long periods of time with no problems. Palms are more
shallow rooted and require water more often. But ten days is not too long for
any of these plants during the winter.

In an ideal world the deeper rooted plants would be on a separate irrigation circuit or valve from shallow rooted plants. Deep rooted desert plants like acacia, palo verde and mesquite would be on a separate circuit from the other non desert deep rooted trees and shrubs. This gives you alot of flexibility in watering.

Palo Verde is another desert tree whose growth can be managed by applying more or less water. Putting desert trees and shrubs on their own separate irrigation circuit gives you this type of flexibility.

The deep rooted plants would include trees and shrubs and deep-rooted woody perennials that die back each year such as Bougainvillea. The shallow rooted plants would include annuals and flowering perennials that die back each year like Lantana. Lawns should be on a separate circuit but could be tied into vegetables as long as the water could be turned off to vegetables between seasonal plantings.

Q. My oranges are turning orange. How long should I wait
before I harvest them.

Yes, oranges and other tender citrus will grow in Las Vegas but not without some careful considerations.

A. Oranges do not necessarily turn orange before they are
ready. Orange color develops due to climate. In the tropics oranges remain
green or green/yellow even when they are
ready to eat.

Fully ripe oranges in the Philippines. They do not turn orange because of the warm climate. The fruit above it is rambutan.

Orange color is induced in oranges that don’t develop good color
using ethylene gas in closed rooms where orange color is important for
marketing and sales. The best way is to pick one and try it. If sufficiently
sweet, harvest the others or wait and harvest when needed during cold months
but leaving them on the tree too long can reduce the number of
flowers in the next cycle of fruit production. When they are ripe start removing them. Cut the stem close to the fruit, don't pull the fruit from the tree, for better storage life.

Handheld refractometer used for measuring total dissolved solids (sugar content) from the juice of fruits and vegetables.

A sophisticated method is to
purchase a small handheld device called a refractometer and measure the sugar
content. Maturity in fruit is usually a measure of the sugar content which the
refractometer will read for you.

Q. Do you have any guidelines for watering fruit trees in
the winter? I cant find anything
specific to winter watering on your web page. I have apricot, nectarine, apple,
fig, pear, plum, cherry, peach, orange - planted spring 2015. I am not expecting
the apple or cherry to make any fruit yet, They are just ornamental. Pomegranite, jujube, lime, grapefruit I planted 3 years ago. Will deep watering once a month suffice for December -
February?

Fruit tree with irrigation basin surrounding the trunk. Irrigation bubbler at the top right of the basin that allows 2 gallons of water to flow from it every minute. The basin must be level so that water flows evenly across its surface.Surrounding the trunk is rabbit protection.

A. Once a month is not even often enough for trees established for years in our warm winter desert climate. Once they have been established, trees established for one season might be closer to every two weeks during the winter. If the soil is very sandy, then once a week. Fruit trees surrounded by dry soils should be watered more often than trees in wet soils. Wet soils in the desert might happen if fruit trees are grown close to a lawn area, a wall that has irrigation applied on the other side of it, intercropped between the trees with other plants like vegetables or herbs.

Irrigation basins surrounding newly planted fruit trees that have been staked and mulched with wood chips. The screening around the trees is for rabbit protection which also keeps the wood mulch away from the trunk. If drip emitters were used, two emitters might be enough for the first 2 to 3 years. When they have reached 2 to 3 years old than increase the number of emitters to at least four.

Generally speaking, if there is a surface mulch of at least three inches, add one to two days in the summer and up to one week in the winter. Sandy soils require more frequent watering with smaller amounts applied. Desert soils should contain 50% compost at the time of planting. Fruit trees perform much better with wood mulches applied to the surface and require less frequent watering.

General Watering Schedule for Fruit Trees
Let me run down a general schedule of watering fruit trees that is ignoring rainfall since we only receive an average of 4 inches (10cm) or rain each year.

Newly planted in spring or fall during cool weather....2-3 days; winter 1 to 2 weeks depending on soil and mulch covering. After growing for one season then assume the trees are established.

Fruit trees established at least one season with fruit or nuts on the tree... Summer every three to four days depending on soil and mulch. Spring and fall, weekly. Winter every two weeks. Fruit trees that have been harvested can be watered less often.

Q. I'd appreciate some pointers on how to arce for fairy duster plant So it becomes healthier and a better looking shrub. Very little has been
done because the bees are usually on it.

Fairy duster and honeybees

A. This plant is native to North and Central America
growing in warm desert climates and soils. This tells you a little bit about
how to manage it. This should tell you to not water every day. Plants like this are usually very susceptible to root rot so make sure the soil has been amended with compost before planting so that it improves drainage.

Fairy duster in the backyard of reader

It will tolerate desert soils as well as infrequent watering.
At planting time I would amend the soil with about 25 to 50% compost and make
the whole about three times wider than its container. I realize yours is
already in the ground so watering and fertilizer applications are important to
mention.

Do not water this plant too often. That will be the biggest mistake
people make. Fertilize it lightly once in the very early spring around late
January or February with a rose type fertilizer. The plant can get 3 feet wide
and 3 feet tall in soils that have been amended with compost.

As long as it's
in a sunny location you should see a profusion of blooms in the spring and
summer months that attract bees, hummingbirds and night flying moths. Quail
like to feed on seed from the seed pods. Rabbits like to browse on new growth.

You can clean up the plant in the early spring by removing dead leaves and
stems. You will encourage more blooms if the plant is in a sunny location and
flowers are removed before they begin to form seedpods.

Q. It seems no matter what brand, no matter where I buy
my potting soil I have to bake it before I can use it. If I don't, I get hundreds of tiny fly that
hatch and swarm. I put out water to
catch and drown them. I spray
insect oil on top of the soil several
times a day. I'm so afraid I'll kill the
plants.

A. Yes, fungus gnats are a big problem in potting soils and they can create damage to plant roots.
They feed off of both decaying plant parts and soft, succulent living roots as
well. Potting soil does not smell very good if you have to put it in your oven at 150° for 15 minutes to kill these nuisance critters.

The larvae can cause damage to new, tender roots of plants. If they are
extremely happy in their environment they can multiply very rapidly and cause
some severe damage. Besides that, they are pesky and a nuisance inside the
house.

This is Garden Gourmet potting soil and I have never seen fungus gnats in this product. However, bagged potting soil that is not been heat treated will carry fungus gnats. This product sells for $5 for one cubic foot.

If potting soil is sterilized with a heat treatment by the manufacturer
it should kill all of the fungus gnats. If the soil is introduced into an
environment where there are fungus gnats present then it will get reinfested
again.Here is what the University of California says about them

They can be controlled with some organic pest control products;
nematodes that go after these larvae and a bacterium which does the same thing.
You should be able to find some of these products in your local nursery or
garden center. I have never used them so I am reporting only what has been reported on the internet using these methods for fungus gnat control. However, cooking them does work.

Another method is to sterilize this potting soil yourself by
placing it moistened into a clear plastic bag in full sunlight and let it bake.
Temperatures need to get up to about 160 F for at least 30 minutes for good
control. Keep in mind that if you introduce this back in the environment where
a fungus gnats are present and they will reinfest this sterilized potting soil.
Another option is to apply pyrethrin to the soil and water it in.

This is a Lantana I saw pruned by a local company. Leaving this much wood remaining will make it very "twiggy" at the base. You can actually prune it much closer to the ground in this.

You can see from this close-up that I took last February that suckering can occur much lower on the stems of Lantana. Don't be afraid to cut it close to the ground. Leave about 1 inch for suckering.

A. Both of these plants are pruned during the winter
months since they both produce flowers on new growth during the summer months.

After pruning, apply a high nitrogen and high phosphorus fertilizer to push new leaf and stem growth and dark green color. The phosphorus will help to promote flowering. Flowering will not occur until the top growth is large enough and comes into balance with the existing root size. This is sometimes referred to as the root to shoot ratio.

I would
delay pruning them until late winter (late January) unless you don’t mind
looking at "dead" space (the space is not occupied by anything). For
lantana it normally freezes during winter months and you have a choice whether
to leave the dead top of the plant in place or cut it down to the ground,
leaving one inch of stems remaining to support the new growth beginning in
February.

You can prune oleander close to the ground, just like Lantana. Cut it back to within 2 to 3 inches of the soil surface. This is the time of year to do it up until about the end of January when it begins to push new growth all by itself.

Because
the roots are fully grown, alive and healthy you will see very rapid growth in
the spring. Fertilize the pruned plant in late January or early February to
encourage new growth and flowers. Use a fertilizer that supports flowering
plants such as a rose fertilizer blend or other fertilizer for flowering
plants.

You can see from this picture that new growth is beginning to sucker from the base just like Lantana. Apply a fertilizer near the base of the plant close to a source of water. Use the same fertilizer as the Lantana. A rose type fertilizer is fine.

Oleander will regrow very quickly when cut back close to the ground, fertilized and watered. This was one month after pruning. Nitrogen in the fertilizer will push leaf and stem growth along with dark green color. Phosphorus in the fertilizer will push flower growth and flower size.

Oleander is pruned at the same time of year as lantana because it also blooms on new growth, not older growth. You can chose to remove 1/3 of the
plant by cutting these largest stems to the ground for renewed growth at the
base or you can cut the entire plant to the ground and let it regrow. Your
choice. Either way you will see luxurious growth and lots of flowers next year.
Again use a fertilizer that supports flower growth and apply it early in the
spring.

This is an example of a fertilizer that will push leaf and stem growth and dark green color. You would apply this immediately after pruning and water it in. A 10 pound bag sells locally for $7.95

This is an example of a fertilizer that it increases the number of flowers and their size. It should be applied about 4 to 6 weeks later. A 10 pound bag also sells for $7.95 .

Thursday, December 3, 2015

Mexicans call them Nopales or Nopalitos. The fruit they call Tunas. These edible cacti were under evaluation at the University Orchard in cooperation with the University of Sonora in Hermosillo.

Fruit or tunas of the nopal cactus under cultivation and evaluation at the University orchard

I will be giving a presentation to the Cactus and Succulent Society on how to grow them as a food crop Thursday night, December 3, at 630 pm at the Garden Clubs building located at Lorenzi Park off of Washington and Rancho.

Nopal cactus ..nopales...under cultivation and evaluation at the University orchard. This is an ideal size and thickness to use as fresh vegetable.

Apple Babe from Dave Wilson Nursery under evaluation in North Las Vegas Nevada

Fuji apple grown in North Las Vegas Nevada

Anna apple grown in North Las Vegas Nevada

When I left the University back in 2011 this program of fruit evaluation for desert environments was no longer continued. Fruit quality is very connected to the terrioror the local environment. This is nothing new and has been noted for many other crops where quality is a desired trait and useful in marketing.I have not had a chance to evaluate this Apple
yet. I like about five seasons of production to get a good evaluation. Just because a plant grows does not necessarily mean the fruit quality is high. Sometimes there is little you can do to influence the quality of a fruit if you do not have a suitable terrior it. Most people think that a good fruit is one that is large, has an appealing color and free from blemishes to be a "good" fruit. How wrong! There are
too many variations because of the climate and weather. The chilling requirement is 800 to 1000 hours according to Dave Wilson Nursery. This may be somewhat problematic for production in the warm desert but not necessarily for fruit quality.I will take a look at
some of the information the orchard has gathered so far on this variety and let you
know. I have not been involved so I hope that the three is still there, there are replications to account for variations and data has been recorded. It ripens a little bit before Granny Smith and a month or so before Pink
Lady. It ripens during a time of the year when flavor should be good considering ONLY the time of year. More information on this and related varieties.

Welcome to Xtremehorticulture

Home. My home base is Las Vegas, Nevada, in the Eastern Mojave Desert. This blog focuses on horticulture in Deserts.

Me. Desert Horticulture is very different from horticulture in wet climates. Very few people talk about it. This blog focuses on it. My experience in horticulture span over 50 years; time as an applied academic and now working as a consultant. This blog shares my experience and advice in Desert Horticulture. Work in Northern, East and Southern Africa, Western and Central Asia and the Middle East have expanded my views on Desert Horticulture.

Questions. I reply to questions sent to me as quickly as possible. Please include pictures. It helps. Unless questions are confidential, I post them on this blog if they add new information.